When bullets are printing sideways on the target, it usually means the barrel twist is not quick enough to stabilize a bullet of that length. How long are the cast 450 grain bullets vs the jacketed ones that are stabilizing? You may be able to fix your issue by just dropping down to a shorter 300 or 350 grain cast bullet.
Taz : It would be interesting to know how you end up with this. Let us know how this works out for you.
Team 45-70 #681 Don't blame me I voted for Mitt.
I have been out to the range 4 more times... with the new .459 cast hollow base the rifle shoots very well at 100 yards. Open sights can put all the shots in a coffee can... I am really pleased with all the help and info from this site.... THANK YOU ALL